1 / 12

Gamma-ray Nova V407 Cyg and Fermi-LAT Galactic Plane Transients

Gamma-ray Nova V407 Cyg and Fermi-LAT Galactic Plane Transients. C.C. Teddy Cheung (NRC Research Associate*) on behalf of the Fermi-LAT Collaboration *resident at Naval Research Lab. Heidelberg Galactic Binaries – 2010 Dec 3. Fermi-LAT Galactic Plane Transients.

wolfe
Download Presentation

Gamma-ray Nova V407 Cyg and Fermi-LAT Galactic Plane Transients

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Gamma-ray Nova V407 Cyg and Fermi-LAT Galactic Plane Transients C.C. Teddy Cheung (NRC Research Associate*) on behalf of the Fermi-LAT Collaboration *resident at Naval Research Lab Heidelberg Galactic Binaries – 2010 Dec 3

  2. Fermi-LAT Galactic Plane Transients Low Galactic latitude blazars in 1st LAT AGN Catalog LAT Galactic plane (|b|<10o) transients from daily search* *Excludes flaring from known sources like Cyg X-3 and Crab 2010 Dec 3 - Cheung

  3. Counterpart Search - Fermi J0910-5041 • Fermi J0910-5041 • (Cheung et al. ATel #1788) • Gal. latitude, b = -1.2o • October 15, 2008 (10σ), 2 day gamma-ray flare • Gamma-ray flare 10x larger than average flux • Swift TOO within 1 day 68% 68% LAT 95% error circle contains Swift XRT source (Landi et al. ATel #1822) coincident w/ flat-spectrum radio source in AT20G & SUMMS (Sadler ATel #1843) • Background blazar? Blazar gamma-ray activity typically more ‘long lived’ • Galactic origin? More follow-up necessary 2010 Dec 3 - Cheung

  4. Counterpart Search - 3EG J0903-3531 • 3EG J0903-3531 • (Hays et al. ATel #1771) • Gal. latitude, b = +7.7o • October 5, 2008 (10σ), 3 day gamma-ray flare • 5x above 3EG flux • Swift TOO within 2 days 68% 68% Updated LAT 95% error circle (8 months) contains a flat-spectrum radio source that is detected with Swift/XRT • Other bright Galactic plane transients • Fermi J1057-6027 (Yasuda et al. Atel #2081) – no ID • Fermi J0109+6134 (Vandenbroucke et al. 2010) - blazar Preliminary 2010 Dec 3 - Cheung

  5. Fermi-LAT Discovery of a Nova • Fermi J2102+4542 (6-8σ) March 13-14(Cheung et al. Atel #2487) • Excellent γ-ray localization (r=3.7’), consistent with symbiotic binary V407 Cyg • Subsequent analysis found initial LAT detection on March 10, same day as nova discovery • First g-ray detection of a nova • White dwarf in binary system LAT 0.2-100 GeV PSR J2021+4026 1FGL J2111.3+4607 Nova 2010 V407 Cygni Abdo et al. 2010 Science, 329, 817 (arXiv:1008.3912) Corresponding authors: Cheung, A.B. Hill, P. Jean, S. Razzaque, K.S. Wood 2010 Dec 3 - Cheung

  6. V407 Cygni: a variable star Symbiotic binary: small white dwarf (WD) star and large red giant (RG) star orbiting each other closely Variability can come from the binary motion, pulsations of the red giant (IR/optical), accretion disk around the white dwarf (UV) Nova thermonuclear runaway on WD surface Nova discovery by Nishiyama & Kabashima IAUC 2199 (2010); H. Maehara (Kyoto) 2010 Dec 3 - Cheung

  7. Panchromatic Lightcurves • Optical peaks first • First γ-ray detection day of nova optical discovery • peak 3-4 days later • duration ~15 days • X-rays peak at ~30 days; substantial rise after γ-rays below detectability • Bright evolving radio source (3-140 GHz): ATel #2506, 2511, 2514, 2529, 2536, 2741, 2905 • ★ • Asymmetric distribution of Red giant and wind radiation as seen by nova shell 2010 Dec 3 - Cheung

  8. V407 Cyg Binary System • Evolved Red Giant (M6 III) with: • Mira-like pulsations (745 day period) • SiO maser emission, D-type symbiotic (wind-accreting) • Anomalous Li abundance • Probable distance ~2.7 kpc • Fast rise and decline of nova indicate massive WD (>1 Msun) . • Orbital period uncertain; binary separation ~4 dayγ-ray peak • RG wind & nova shell velocities inferred from optical spectral line-width measurements 2010 Dec 3 - Cheung

  9. V407 Cyg Binary System . Asymmetric distribution of material from Red Giant wind 2010 Dec 3 - Cheung

  10. Nova γ-ray and X-ray Evolution • Nova shell initially freely expands into asymmetric dense medium • Shell toward RG slows down quickly • Gamma rays peak early when efficiency for pion and inverse-Compton processes is favorable • Shell decelerates slowly away from RG • Later X-rays peak, flux increasing with volume of shock-heated gas White dwarf at center Credit: S. Razzaque 2010 Dec 3 - Cheung

  11. γ-ray Spectrum and Energetics 15-day average • Gamma-ray emission process could be: • pion: acceleratedp’s collide with ambient material producing0with prompt decay • inverse Compton: accelerated electrons up-scattering infrared photons from the red giant 2010 Dec 3 - Cheung

  12. Nova V407 Cygni Highlights & Thoughts • Some Fermi-LAT Galactic plane γ-ray transients still unidentified • V407 Cyg first γ-ray nova (white dwarf in binary system) • Fermi acceleration in nova shell; interaction with massive red giant wind plays important role • Shell evolution recapitulates SNR evolution in miniature, and scaled down in timescale • Gamma-ray nova V407 Cyg 2010 not necessarily unique; symbiotic binaries relatively common, novae are numerous • Related binary systems? GX 1+4 = red giant (M6 III) + neutron star. GRS 1915+105 K-giant + black black. 2010 Dec 3 - Cheung

More Related